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25%+ increase in milage <SNAP> - SUNOCO ULTRA 94

9491 Views 31 Replies 16 Participants Last post by  Insightful Trekker
This is my first post here. The reason is, I have had nothing to contribute since getting my brand new 2004 CVT several months ago and visiting this site prior to this. But the time has come!

The weather here in NJ has been in the mid to low 40's for some time now and continues in this range. My mileage has been 50 - 52 mpg during this time.

Last week it was time to fill the Insight up. Having read a number of posts here regarding premium fuel, both pro and con, I thought I would give it a shot. I filled it up with SUNOCO ULTRA 94 octane and reset my FCD. After about 75 miles of driving the MPG was stabilizing between 68 - 70 MPG! After another week of driving 300+ miles, the MPG remains the same, 68 - 70 MPG! No difference in temperature, no difference in driving habits or terrain, essentially no difference at all... except the fuel.

Now I understand that there are all sorts of varying opinions regarding this issue, many with what seems to be a good 'scientific' basis or reasoning as to why this mileage increase can not be attributed to the type of fuel. But facts are facts. And I must engage in a psychotic break with the interpretation of reality to deny that use of this particular fuel does not have a dramatic effect on the increased mileage of the vehicle.

I would suggest strongly the use of SUNOCO ULTRA 94 to increase the MPG, or at least try it. For those who may use this fuel and do not have such success, you too must face the reality of your experience, but I would suspect that it has something more to do with engine performance issues than the fuel. Keep in mind, my vehicle is brand new (7.5K miles to date).
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Any octane fuel will knock, you simply have to advance the timing sufficiently. Optimal timing varies by octane and other engine parameters, as I outlined above. Optimal timing and engine "life" allows for some _slight_ knock. A little simply means your on the peak of the curve.

Sorry figgy but I'm pretty sure about this. Its not cutting edge technology. AFAI remember it dates to the 70's. Generally restricted to performance vehicles until emissions requirements made it increasingly common in the early 90's.

HTH! :)
My dummy comment was not because I was unhappy ':oops:', it was to point out how smart the engineers are to have thought up their nifty solution! :roll:

Is this what the 'ignition timing advance' parameter tracks?

If so, what are normal operating ranges for that parameter?
Gave it a try...

I read the post and thought that I'd give the miracle mix a try.

I filled up my tank and took a 50 mile trip down to my boat. At first it seemed to be working. I got 65.5mpg on the trip and thought WOW.

Over the life of the tank however, it's dropped to 58.3mpg. I hardly concider this an increase because I averaged 55.1mpg on the regular unleaded tank before.

I think the Ultra 94 does have an improvement on your miles per gallon, but it'll be in the range of 2-4mpg. This is hardly worth paying the primium of $.20+ more a gallon. For those of you CVT owners who are trying to figure out how I got the 65.5mpg trip to my boat. I think it had to do with 1) It was a warm day 2) I was heading to the Chesepeake Bay so the elevation was downhill the whole way 3) we recently had a low pressure system move through and I was getting a funky tailwind from the north east that was pushing me the whole way there.

- Brenton
Hi Brenton,
No comments here on the gas as I've never tried it, but I had to comment on your trip to your boat on the Chesapeake because it's one of the primary reasons I bought a used Insight. My sailboat is on the Bohemia River in the upper Bay, and it's a 135 mile round trip from where I live, and the Insight saves me alot of money gas wise.

Anyway, it was just nice to run across a fellow Insight owner who is also a Chesapeake Bay boater!

94 octane does give better gas mileage and I only use 94 octane in my car and will not use a lower grade octane.... however this isn't the only reason I buy this gas I don't think I've seen anyone post that it is a cleaner burning gas as well...!
Ultra 94

I thought that I'd treat my insight to a tank of the GOOD stuff as I could afford it getting 50 plus MPG. The car ran the worst it ever did, BUT the good news is that since that one tank, I've been putting just regular gas in (LOW OCTANE) and have consistantly gotten better than 70 MPG since. I'm not sure if it was due to the higher octane or maybe I'm learning better how to drive it. I did however block off the radiator and that did help a lot. the temperature only went up one more bar over normal and made a notable difference in the mileage. :D
Hey Jerry,
I would be careful about 1 bar over normal. After connecting an OBD readout to my laptop, I have seen 203 degrees on it without any increase in the number of bars. AFAIK, the fan has never come on, but I have different sized radiator blocks and monitor it consistently to make sure I don't get it too hot. I've never seen mine over the six bars on the display and it will go from 193 to 203 with no change.
If it hits 199 on a hill, I usually take out the radiator block or go to a smaller one. After fooling around with this, I pretty much know what I should start out with in the morning based on the thermometer on the carport wall.
Hey Jerry... something you have to know I have been in contact with some of the major fuel experts for imperial, Sunoco, Petro Canada....

I believe 94 octane is also an ethanol gas.... from what I heard from them is that its not adviseable to use ethanol then go back to regular gas... eg... in other words always use ethanol gas if that is the route you take ... according to my source... eg... its better for your engine and less pollution.... so trying a higher grade octane gas with ethanol eg.. only once will not provide you with better figures...

I would never consider using a lower grade gas for more than just mileage reasons...

A. Carbon buildup (egr problems to come)
B. Cleaner burning..
C. lastly mileage....
Higher Octane - less power per unit?

I thought Octane was an additive that prevents pre-detonation in high compression engines. It doesn't add to the combustive power per unit (lesser percentage of gas). It just allows higher compression engines to operate without ill timed detonation. With less power per unit (any measurement) it would make sense that the mileage would go down. Does premium gas have other additives (detergents - or is that brand dependent?) that may be beneficial? Would it justify .20 more a Gal. I also understand that all other gas additives (Ethanol - MTBE) have a lower energy output per unit than gas = giving less power. This would translate to lower MPG and higher emissions overall since more fuel would be necessary to go a given distance.

Please remember that I am not speaking from authority on the subject. Just from what I have read on the subject and using country common sense.

My first post - just bought a 2001 Insight last week and I really love driving it. I intend to up the PSI on the tires and drive more conservatively - right now I go anywhere between 80 - 90 MPH (traffic speed) for the better part of a 150 mile daily commute.
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Re: Higher Octane - less power per unit?

Kuma said:
right now I go anywhere between 80 - 90 MPH (traffic speed) for the better part of a 150 mile daily commute.
You'd better slow that thing down!
Slow that vehicle down

And slow down I shall .....actually, I just did a MPG check this morning after modifying my driving habits some. Although I still must go 80-85 and sometimes 90 MPH on the way to work - I do it much less often. Going to work I must sustain a faster speed and it is reflected in my MPG average for that leg of the journey (about 55 MPG). I got over 75 MPG on the way back for an overall average in the mid 60s. I monitored the instantaneous MPG readout and drove more in the slower lanes. I've yet to inflate the tires to higher PSI - I'll be buying a pressure indicator tomorrow. By going between 55 - 60 MPH my gauge stayed over 100 MPG.
Re: Higher Octane - less power per unit?

Hi Kuma,

You are correct in that higher octane fuels have less heat energy. The precise term is detonation not to be confused with pre-ignition (a much more serious mistimed burning of the fuel).

From all the many and different locations of Insighters that have tried premium fuels the additional cost never is offset by the slightly better MPG. However there are other benefits mainly low sulphur. Sulphur will ultimately kill a CAT.

The difference in better MPG from a lower "heat" content fuel can be explained by the time factor for the burn process. By having a fuel with higher octane ignition timing can be advanced to an eariler point since detonation is in part due to peak combustion chamber pressures occurring too early and the piston pushing against this out of time force. This also allows for more complete combustion (more burn time from an earlier spark and slower burning fuel allowing for peak combustion chamber pressures to properly coincide with piston position). Therefore better MPG can be achieved.

SEE the paragraph Energy Content and World War II and Octane:

and an old post here: ... php?t=2978

HTH! :)
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